Wireless communication systems, including data communication systems, have been under continual development for many years. In some applications, there is a desire to determine the directionality of communications transmitted from one wireless device to another.
For example, Bluetooth (BT) Public Indoor Positioning (PIP) (also referred to as HAIP—high accuracy indoor positioning) is one direction finding technique that is based on a single-antenna wireless device (e.g., a Locator) locating position-fixed wireless devices (e.g., Targets or Tags). The BT PIP tags utilize multiple transmitting antennas to allow the BT PIP locator to estimate an Angle of Departure (AoD) of the communications transmitted by the BT PIP tags.
High accuracy asset tracking (HAAT) is another direction finding technique similar to BT PIP, but where a HAAT locator includes multiple antennas to enable the HAAT locator to estimate an Angle of Arrival (AoA) of communications received from a single transmitting antenna of the HAAT tag.
Angle of arrival (AoA) measurement is a method for determining the direction of propagation of a radio-frequency wave incident on an antenna array. AoA may determine the direction by measuring the Time Difference of Arrival (TDOA) at individual elements of the array, from which these delays can be used to estimate the AoA. In some implementations, the TDOA measurement is made by measuring a difference in received phases at each element in the antenna array.
An application of AoA may include aiding in the determination of a geodesic location or geolocation of a wireless device, such as a mobile phone. The aim is either to comply with regulations that require cell systems to report the location of a cell phone placing an emergency (i.e., 911) call or to provide a special service to tell the bearer of the cell phone where he is. One or more base stations (or other wireless devices) could combine measurements obtained from several AoA measurements to determine the mobile phone's location.